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Author Topic: Combining Loadcases (Mechanical + Thermal)  (Read 21746 times)

HughG

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Combining Loadcases (Mechanical + Thermal)
« on: September 24, 2009, 05:05:34 PM »
I was attempting to use HyperSizer to combine some Thermal loads with some Mechanical loads for analysis. My understanding is that you should be able to combine a Mechanical subcase with a Thermal subcase. I originally had the thermal subcases in a separate deck and imported it into HyperSizer via the Setup form. ERROR - HyperSizer cannot import more that one Thermal subcase. Not a problem I thought, I'll just split the subcases into separate decks. HyperSizer then read the loads in fine. With the Mechanical subcases already in there, I then tried adding new load cases on the 'Load Cases' tab. PROBLEM - I can't combine Mechanical and Thermal cases between run decks. I can only combine Mechanical & Thermal from the same Run deck.
This effectively means that you can only have one Thermal case applied to a Mechanical case. Is this the way it's supposed to be? If so, are you planning add some flexibility in the future? The GUI seems to already be set up to allow a more flexible combination of Mechanical & Thermal cases.
If you do plan to address this, then maybe you could also consider going a bit further and allowing the user to combine two or more of any case, similar to a Nastran SUBCOM & SUBSEQ statement. Combining cases with factors would be really useful if you wanted to say apply a reversible load (vibration load) to an existing mechanical set e.g (Case 3 = Case 1 + Case 2) & (Case 4 = Case 1 - Case 2).
 

Phil

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Re: Combining Loadcases (Mechanical + Thermal)
« Reply #1 on: September 25, 2009, 10:42:10 AM »
The assumption that HyperSizer is making here is that each mechanical load case will only ever be paired with one thermal load case.  So the idea is that you would have the mechanical load sets in the same run-deck as the thermal load sets that they correspond to.  We don't allow a mechanical case to be paired with other thermal cases.  However, you can always copy your mechanical case into the second run-deck (all you have to do is copy the SUBCASE from the case control from run-deck A to run-deck B and give it a new number).   We don't have any plans to change this right now.

I can see the appeal of combining more loads together (like a nastran SUBCOM), but again, we don't have plans to do this.  FYI however, if you do use SUBCOMs in Nastran, HyperSizer does support these correctly.

HughG

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Re: Combining Loadcases (Mechanical + Thermal)
« Reply #2 on: October 06, 2009, 02:38:20 PM »
Thanks for your reply Phil,
I realized I could copy my mechanical cases into other run decks, but it's the re-numbering of the mechanical cases that bothered me. It's not the solution I'm looking for.
Also, I did see that you support SUBCOMs correctly, but unfortunately using the SUBCOM in Nastran is limited to the type of solution being run. For instance, I can't combine subcases from two different types of solutions, nor can I combine cases that use different PARAM cards (e.g. Inertia relief).
I could use a script to combine f06 loads and create a new f06, but I think it would be far more appealing if HyperSizer could do it.